Surgery on the central nervous system requires entry through the dura mater, hereinafter "dura", a connective tissue membrane which surrounds the brain, spinal cord and nerve roots and which is filled with cerebrospinal fluid. To provide an opening, normally a section of dura is removed or the dura is cut to create a flap. Sometimes traumatic injury causes an opening in the dura. Quite often, the opening cannot be closed by sewing the dura to itself because the amount of remaining dura is insufficient or the quality of the dura near the opening is unsatisfactory. Closure may be achieved by covering the opening with a patch and attaching the patch to the dura with sutures.
Numerous perforations are made when the patch is sewn to the dura. This has the shortcoming that fibroblast growth in and around the perforations during normal healing leads to scar formation between the dura and underlying neural structures. The scar can cause underlying neural structures to adhere to the dura, preventing free movement of the structures within the cerebrospinal fluid. Such constraint may create tension involving a peripheral nerve or the spinal cord which produces pain. During normal body motion such constraint also is hypothesized to disturb the brain so as to increase frequency of seizures.
The need is not uncommon for the surgeon to reopen the dura in order to operate again. Reopening is occasionally required, for example, to remove a recurrent tumor or an epileptic portion of the brain. If substantial scar has connected the dura to the underlying neural structure, the surgeon may have to exercise extraordinarily great care to detach the dura without causing increased nerve damage during the later operation. Hence, conventional methods of patching a dural opening can increase the technical difficulty, and consequently, the morbidity of the procedure.
Attachment between dura and the underlying neural structure can be reduced by using patches of effectively nonadhesive materials. Still, some scar formation in the perforations and on suture threads which protrude through the patch and below the dura is expected to attach the dura to neural structure.
The primary object of the present invention is to provide a plentiful, tough, pliant and lubricious dural patch that generally minimizes scar tissue adhesion between body connective tissue membranes and adjacent organ tissue, and particularly, between dura and the underlying neural structures. More specifically, it is an objective to provide a dural patch which can be implanted in a manner that prevents scarring between the patch securement sutures and brain or spinal column.
Accordingly, there is provided an implantable prosthesis comprising
a patch of lubricious, biologically benign material having a perimeter and having a patch flange extending inward from the perimeter by a lap distance; and PA1 a suture flange attached to one side of said patch, wherein said suture flange overlaps said patch flange. PA1 (i) placing within the opening and inside of the body membrane to completely close the opening, a prosthesis comprising: PA1 (ii) lapping the lip and the suture flange; and PA1 (iii) attaching the suture flange to the lip.
There is further provided a process for closing an opening in a body membrane, said opening having a lip, including the steps of
a patch of lubricious, biologically benign material having a perimeter and having a patch flange extending inward from the perimeter by a lap distance; and PA2 a suture flange attached to one side of said patch, wherein said suture flange overlaps said patch flange;
Generally, the suture flange is attached to the lip by sewing sutures in a circuitous path along the lip of the opening at a location on the suture flange inboard of the patch perimeter and in a way that the sutures do not penetrate the patch.